The invention relates to a device for enabling the load of a lifting appliance to be controlled.
During use of the lifting appliance it is desirable, if not imposed by the regulations, to know at any time if the load which is actually applied reaches a limiting value or not, determined, for example, by the manufacturer as a function of the geometrical characteristics of the appliance, the position of the point of application of the load, the conditions of operation, and the mechanical strength of the parts of the appliance.
In general, the manufacturer supplies with the appliance charts indicating the maximum authorised loads as a function of various geometric parameters of the appliance, for example the radius, and as a function of the conditions of operation, such as whether, in the case of an appliance on wheels, it rests on these wheels or is supported by outriggers.
It has already been proposed to measure the load actually raised by the appliance and to compare it with the limiting value, with a view to giving an alarm signal and/or stopping the machine from operating if this limiting value is reached or exceeded.
However, these previous devices present various disadvantages. In fact, they are difficult to use, particularly because of the movements which the operator has to carry out. They are not reliable because of their too great sensitivity to external conditions, they are fragile because of their complexity, they are costly, and they are not applicable to various types of appliance without modification of the appliances of the devices themselves.